Vehicle twist axle assembly
The twist axle assembly includes a pair of spaced apart trailing arms and a twist beam of which extends in a first direction between the trailing arms. The twist beam includes a pair of end portions and a middle portion. The twist beam further has a pair of side walls and at least one additional wall that extends between the side walls. The side walls in the middle portion are generally parallel with the side walls of the end portions. The twist beam is generally hour-glass shaped with the middle portion having a first width and the end portions have a greater second width. The twist beam also tapers from the first width of the middle portion to the second widths of the end portions for gradually increasing a torsional stiffness from the middle portion to the end portions.
This U.S. National Stage Patent Application claims the benefit of PCT International Patent Application Serial No. PCT/US2016/017284 filed Feb. 10, 2016 entitled “Vehicle Twist Axle Assembly,” which claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 62/118,748 filed Feb. 20, 2015, the entire disclosures of the applications being considered part of the disclosure of this application, and hereby incorporated by reference.
BACKGROUND OF THE INVENTION 1. Field of the InventionThe present invention is related, generally, to vehicle twist axle assemblies.
2. Related ArtA twist beam rear axle suspension assembly, also known as a torsion axle assembly, is a type of automobile suspension system including a pair of trailing arms, each of which is coupled with a wheel of a vehicle and with an axle of the vehicle, and a twist beam which extends transversely between the trailing arms. During operation of the vehicle, the twist beam deforms in a twisting movement when one of the wheels moves relative to another, such as during vehicle body roll or when one of the wheels encounters, for example, a pothole or an obstacle in a road. The twisting movement of the twist beam absorbs this movement to make the ride more comfortable for occupants in the vehicle body.
In order to provide the twist axle assembly with desirable performance characteristics, the entire length of the twist beam is provided with a relatively low torsional stiffness as compared to the trailing arms, thereby allowing the trailing arms to pivot relative to one another. However, this configuration may result in abrupt changes in torsional stiffness about the twisting axis at the joints between the twist beam and the trailing arms, and these abrupt changes in the torsional stiffness of the twist axle assembly at these joints could compromise the structural integrity of the joints.
One approach to improve the structural integrity of the joints between the twist axle and the trailing arms is to vary the torsional stiffness of the twist axle so as to reduce the differences in the torsional stiffnesses of the twist beam and the trailing arms at the joints. For example, one type of twist beam is configured with a crush tube design where the center area is generally V-shaped with angled, double walls and opposite end portions have closed geometrical shapes. The V-shaped center portion has a relatively lower torsional stiffness than the rectangular or circular end portions, and the twist axis is also provided with intermediate sections which transition between the V-shaped center portion and the stiffer end portions. Another approach is to add pieces to the twist beam adjacent the trailing arms to make the transition more gradual.
SUMMARY OF THE INVENTION AND ADVANTAGESOne aspect of the present invention is for a twist axle assembly for use in a vehicle. The twist axle assembly includes a pair of spaced apart trailing arms and a twist beam of a single piece which extends in a first direction between opposite ends that are operably connected with the trailing arms. The twist beam includes a pair of end portions and a middle portion which extends between the end portions. The twist beam further has a pair of side walls and at least one additional wall that extends between the side walls. The twist beam is generally hour-glass shaped with the middle portion having a first width in a second direction that is generally transverse to the first directions and the end portions have a greater second width in the second direction. The twist beam also tapers from the first width of the middle portion to the second widths of the end portions for gradually increasing a torsional stiffness from the middle portion to the end portions.
In use, the reduced torsional stiffness of the twist beam in the middle portion causes the majority of the twisting stresses from relative rotation of the trailing arms to be absorbed by the middle portion of the twist beam. This has the effect of protecting the joints between the ends of the twist beam and the trailing arms from damage that could result from twisting in the end portions. Additionally, the generally parallel relationship between the side walls of the middle portion and the end portions allows the twist beam to be made very cost effectively through stamping.
According to another aspect of the present invention, the side walls of the middle portion are generally parallel with the side walls in the end portions.
According to yet another aspect of the present invention, the side walls of the middle portion are within three degrees of being exactly parallel with the side walls in the end portions.
According to still another aspect of the present invention, the twist beam has a top wall and a bottom wall, and the middle portion has an opening formed into the bottom wall for further reducing the torsional stiffness of the middle portion in comparison to the end portions.
According to a further aspect of the present invention, the side walls of the middle portion include a plurality of apertures for further reducing the torsional stiffness of the middle portion in comparison to the end portions.
According to yet a further aspect of the present invention, the twist beam is generally U-shaped with the wall extending between the side walls being a top wall.
According to still a further aspect of the present invention, the ends of the twist beam are secured with the trailing arms through welding.
According to another aspect of the present invention, at least a portion of each of the end portions of the twist beam has a closed geometric profile.
Another aspect of the present invention is related to a method of making a twist axle assembly for a vehicle. The method includes the step of providing a pair of trailing arms. The method continues with the step of stamping a workpiece of sheet metal into a twist beam. The as-stamped twist beam has a pair of end portions and a middle portion that extends in a first direction between the end portions. The twist beam further includes a pair of side walls and at least one additional wall that extends between the side walls. Also, the twist beam is generally hour-glass shaped with the middle portion having a first width in a second direction, which is generally transverse to the first direction, and the end portions have a greater second width in the second direction. The twist beam tapers from the first width of the middle portion to the second widths of the end portions for gradually increasing a torsional stiffness of the twist beam from the middle portion to the end portions. The method proceeds with the step of attaching the twist beam with the trailing arms.
According to another aspect of the present invention, the side walls in the middle portion of the twist beam are generally parallel with the side walls in the end portions.
According to still another aspect of the present invention, the twist beam has a top wall and a bottom wall, and the middle portion has an opening formed into the bottom wall for further reducing a torsional stiffness of the middle portion in has an opening formed into the bottom wall for further reducing the torsional stiffness of the middle portion in comparison to the end portions.
According to a further aspect of the present invention, the side walls of the middle portion include a plurality of apertures for further reducing the torsional stiffness of the middle portion in comparison to the end portions.
According to yet a further aspect of the present invention, at least a portion of each of the end portions of the twist beam has a closed geometric profile.
According to still a further aspect of the present invention, the step of attaching the twist beam with the trailing arms is further defined as welding the twist beam with the trailing arms.
These and other features and advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a first exemplary embodiment of an improved twist axle assembly 20 for a vehicle suspension system is generally shown in
The twist beam 24 extends in a first direction between opposite ends and includes a pair of opposing end portions 26 and a middle portion 28 which extends between the end portions 26. The exemplary twist beam 24 is generally symmetrical in shape about a lateral midpoint of the twist beam 24. The end portions 26 of the twist beam 24 are connected with the trailing arms 22 for allowing the trailing arms 22 to rotate relative to one another during operation of the vehicle. The trailing arms 22 could have any suitable shapes or configurations. Both the twist beam 24 and the trailing arms 22 are preferably made of metal (such as, for example, steel, steel alloy, aluminum, aluminum alloys, magnesium, magnesium alloys, etc.).
Referring still to
Referring now to
As shown, the end portions 26 of the twist beam 24 have closed (or nearly closed) geometrical profiles, and the middle portion 28 has an open, and uncrushed, geometrical profile. Specifically, the end portions 26 have generally rectangular shapes with a top wall 34 and a bottom wall 36 that extend between the side walls 30, and the middle portion 28 is generally U-shaped. In contrast to crushed tube-style twist beams, the exemplary middle portion 28 is single walled, and the open geometrical configuration is provided by an opening 38 in the bottom wall 36. This configuration further reduces the torsional stiffness of the middle portion 28 in comparison to the end portions 26 to further protect the weld joints between the twist beam 24 and the trailing arms 22. The opening 38 is generally elliptical or oval in shape such that the torsional stiffness of the twist beam 24 transitions gradually from a minimum torsional stiffness at an approximate midpoint of the middle portion 28 to the end portions 26, and the opening 38 extends at least partially into the side walls 30 (as shown in
The side walls 30 in the middle portion 28 extend parallel or nearly parallel with one another and with the side walls 30 of the end portions 26. Specifically, in the exemplary embodiment, the side walls 30 of the middle portion 28 are angled relative to the side walls 30 of the end portions 26 by less than approximately three degrees (3°). This angle range allows for a stamping die draft during the manufacturing of the twist beam 24 to allow for low cost and highly efficient manufacturing.
Referring now to
Another aspect of the present invention is a method of making a twist axle assembly 20 for use in a vehicle suspension system. The method includes the step of providing a pair of trailing arms 22. The method continues with the step of stamping a workpiece (such as a generally planar blank) into a twist beam 24 with a pair of end portions 26 and a middle portion 28 that extends in a first direction between the end portions 26. The twist beam 24 has a pair of side walls 30 and at least one additional wall that extends between the side walls 30. The side walls 30 in the middle portion 28 are generally parallel with the side walls 30 in the in the end portions 36. The twist beam 24 is generally hour-glass shaped with the middle portion 28 having a first width W1 in a second direction, which is generally transverse to the first direction, and the end portions 26 have a greater second width W2 in the second direction. The twist beam 24 tapers from the first width W1 in the middle portion 28 to the second width W2 of the end portions 26 for gradually increasing a torsional stiffness of the twist beam 24 from the middle portion 28 to the end portions 26. The method proceeds with the step of attaching the end portions of the twist beam 24 with the trailing arms 22.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the appended claims.
Claims
1. A twist axle assembly for a vehicle, comprising:
- a pair of spaced apart trailing arms;
- a twist beam of a single piece, said twist beam extending in a first direction between opposite ends that are secured with said trailing arms, and said twist beam including a pair of end portions and a middle portion which extends between said end portions;
- said twist beam having a pair of side walls and at least one additional wall extending between said side walls;
- said at least one additional wall of said twist beam having, along an entire length of said middle portion which extends on both sides of and across a midpoint of said twist beam, a constant first width in a second direction that is generally transverse to said first direction;
- said at least one additional wall of said twist beam having, in each of said end portions, a second width in said second direction, said second width being greater than said first width, and wherein said at least one additional wall of said twist beam tapers from said first width of said middle portion to said second widths of said end portions for gradually increasing a torsional stiffness of said twist beam from the middle portion to the end portions; and
- in said middle portion, said twist beam being single-walled and having a U-shaped open geometrical configuration as viewed in cross-section.
2. The twist axle assembly as set forth in claim 1 wherein said side walls in said middle portion are generally parallel with said side walls in said end portions and are offset from said side walls in said end portions in said second direction.
3. The twist axle assembly as set forth in claim 2 wherein said side walls in said middle portion are within three degrees of being exactly parallel with said side walls in said end portions.
4. The twist axle assembly as set forth in claim 1 wherein said at least one additional wall of said twist beam is a top wall and wherein said twist beam further includes a bottom wall and wherein said middle portion has an opening formed into said bottom wall for further reducing the torsional stiffness of said middle portion in comparison to said end portions.
5. The twist axle assembly as set forth in claim 1 wherein said side walls of said middle portion include a plurality of apertures for further reducing the torsional stiffness of said middle portion in comparison to said end portions.
6. The twist axle assembly as set forth in claim 1 wherein said twist beam is generally U-shaped with said at least one additional wall extending between said side walls being a top wall.
7. The twist axle assembly as set forth in claim 1 wherein said end portions of said twist beam are secured to said trailing arms through welding.
8. The twist axle assembly as set forth in claim 1 wherein at least a portion of each of said end portions of said twist beam has a closed geometric profile.
9. A method of making a twist axle assembly, comprising the steps of:
- providing a pair of trailing arms; and
- stamping sheet metal into a twist beam with a pair of end portions, a middle portion that extends in a first direction between the end portions and extends across a midpoint of the twist beam, a pair of side walls, at least one additional wall that extends between the side walls, the additional wall having, along the entire length of the middle portion, a first width in a second direction that is generally transverse to the first direction, the at least one additional wall, in each of the end portions, having a second width in the second direction, the second width being greater than the first width, and the at least one additional wall tapering from the first width of the middle portion to the second widths of the end portions for gradually increasing a torsional stiffness of the twist beam from the middle portion to the end portions; and
- attaching the twist beam with the trailing arms.
10. The method as set forth in claim 9 wherein the side walls in the middle portion of the twist beam are generally parallel with the side walls in the end portions and are offset from the side walls in the end portions in the second direction.
11. The method as set forth in claim 10 wherein the side walls in the middle portion of the twist beam are within three degrees of being exactly parallel with the side walls in the end portions.
12. The method as set forth in claim 9 wherein the at least one additional wall of the twist beam is a top wall and a bottom wall and wherein the middle portion has an opening formed into the bottom wall for further reducing the torsional stiffness of the middle portion in comparison to the end portions.
13. The method as set forth in claim 9 wherein the side walls of the middle portion include a plurality of apertures for further reducing the torsional stiffness of the middle portion in comparison to the end portions.
14. The method as set forth in claim 9 wherein at least a portion of each of the end portions of the twist beam has a closed geometric profile.
15. The method as set forth in claim 9 wherein the step of attaching the twist beam with the trailing arms is further defined as welding the twist beam with the trailing arms.
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Type: Grant
Filed: Feb 10, 2016
Date of Patent: Aug 13, 2019
Patent Publication Number: 20180029434
Assignee: Magna International Inc. (Aurora)
Inventors: Abhinand Chelikani (Troy, MI), Patrick Daniel Moritz (Meschede), Johannes Peter Halbauer (Theresienfeld), Sukhdeep Singh (Bakersfield, CA), Kevin Richard Langworthy (Davisburg, MI)
Primary Examiner: James A English
Application Number: 15/550,984
International Classification: B60G 21/05 (20060101); B60G 11/18 (20060101); B60B 35/00 (20060101); B60B 35/12 (20060101);